One of the challenges for the regenerative medicine technique using a multipotential stem cell (hereinafter also simply referred to as “stem cell”), such as an induced pluripotent stem cell (iPS cell) or an embryonic stem cell (ES cell), is how to prevent the risk that the stem cell might remain in an undifferentiated state, be transplanted into a patient's body together with its differentiated cell, and be tumorigenically transformed or become cancerous in the patient's body in transplantation into the patient's body after differentiating the stem cell into a desired type of cell.
Patent Literature 1 discloses a method for determining the differentiation status of a stem cell by detecting a sugar chain specific for the cell using a lectin capable of binding to the sugar chain as a technique usable for evaluating the contamination of the undifferentiated stem cell which might have tumorigenicity. This method involves detecting an undifferentiated sugar chain marker having the sugar chain structure of “Fucα1-2Galβ1-3GlcNAc” and/or “Fucα1-2Galβ1-3GalNAc” using a recombinant protein of a lectin called BC2LCN lectin (rBC2LCN lectin). rBC2LCN lectin is a recombinant protein obtained by expressing BC2LCN lectin (GenBank Accession No. YP_002232818) corresponding to the N-terminal domain of BC2L-C protein derived from a gram-negative bacterium (Burkholderia cenocepacia) in transformed Escherichia coli, and recognizes the above sugar chain structure.
Patent Literature 2 discloses a method for detecting an undifferentiated stem cell remaining after differentiation induction treatment by detecting the above sugar chain in the stem cell culture supernatant using rBC2LCN lectin. Patent Literature 2 has identified a complex carbohydrate, podocalyxin, as an undifferentiated sugar chain marker having the sugar chain structure of “Fucα1-2Galβ1-3GlcNAc” and/or “Fucα1-2Galβ1-3GalNAc”.